So, this is a redesign. I was told that old Windmills (used for milling) evolved to have an even number of removable blades. This allowed the mill to continue operating, while repairing a damaged blade -- simply remove the opposing blade, during repairs.
This is generally true. Mill or pumping turbines generally have a lot of blades (for higher torque), which obviously increases the risk of blade failure. That can be offset by having designs which aren't decommissioned by blade loss.
Of course, that's much less appealing for commercial installations, where access to the blades is expensive and difficult.
edit: also, even blade counts on big, high-powered turbines tend to get into problems with resonance by being symmetrical.
